Electric-control spray nozzle type ammonia gas injection system used for tail gas treatment of diesel engine

Abstract

The invention discloses an electric control spray nozzle type ammonia gas injection system used for tail gas treatment of an automobile diesel engine. The electric control spray nozzle type ammonia gas injection system comprises a liquid ammonia tank, a liquid level temperature sensor, an electric heating rod, an ammonia gas decompressor, a pressure stabilizing tank, a pressure temperature sensor, an electric-control ammonia gas spray nozzle and a controller, wherein the liquid ammonia tank is fixedly arranged on a frame; liquid ammonia is stored in the liquid ammonia tank; the liquid level temperature sensor and the electric heating rod are integrated in the liquid ammonia tank; the liquid ammonia tank is connected with the ammonia gas decompressor through a pipeline; the ammonia gas decompressor is connected with the pressure stabilizing tank through a pipeline; the pressure stabilizing tank is fixedly arranged on the frame; the pressure temperature sensor is integrated on the pressure stabilizing tank; the pressure stabilizing tank is connected with the electric-control ammonia gas spray nozzle through a pipeline; the ammonia gas spray nozzle is mounted on a gas exhaust tube of the automobile engine; and the controller is electrically connected with the liquid level temperature sensor, the electric heating rod, the pressure temperature sensor and the electric-control ammonia gas spray nozzle separately. The invention also discloses a control method for the electric control spray nozzle type ammonia gas injection system used for tail gas treatment of the diesel engine.

Description

technical field [0001] The patent of the present invention belongs to a vehicle diesel engine exhaust post-treatment system. Liquid ammonia is used as a reducing agent for diesel engine nitrogen oxides (NOx), in particular to an electronically controlled nozzle-type ammonia injection system for diesel engine exhaust treatment. Background technique [0002] With the implementation of the National IV emission regulations for commercial vehicles, the vehicle must be equipped with after-treatment devices for nitrogen oxide (NOx) emissions. [0003] China's medium and heavy-duty diesel engines generally adopt the selective catalytic reduction (SCR) technology route, that is, the standard vehicle urea aqueous solution is injected into the exhaust, and the ammonia gas (NH 3 ) for selective catalytic reduction of NOx to produce harmless nitrogen (N 2 ) and water (H 2 O). [0004] Urea solution has obvious disadvantages as a reducing agent: it freezes in winter and needs more than...

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Problems solved by technology

[0004] Urea solution has obvious disadvantages as a reducing agent: it freezes in winter and needs more than half an hour of heating to thaw before it can work normally; low temperature performance is poor, and a high exhaust temperature is required to fully convert into NH 3 , when running under urban conditions with low exhaust gas temperature, it is necessary to add insulation materials to the exhaust pipe and install a burner in front of the catalytic converter to increase the temperature to ensure sufficient conversion of urea, otherwise it is easy to generate a large number of crystals, resulting in exhaust gas The pipeline is blocked, which affects the operation of the vehicle; the urea production process is high in energy consumption and high pollution, and the ratio of vehicle urea aqueous solution requires pure water, and the pure water production process consumes 3 times the normal water

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